flex -- (the act of flexing; "he gave his biceps a flex to impress the ladies")
Overview of verb flex
The verb flex has 5 senses
flex -- (contract; "flex a muscle")
flex -- (exhibit the strength of; "The victorious army flexes its invincibility")
bend, flex -- (form a curve; "The stick does not bend")
flex, bend -- (bend a joint; "flex your wrists"; "bend your knees")
flex, bend, deform, twist, turn -- (cause (a plastic object) to assume a crooked or angular form; "bend the rod"; "twist the dough into a braid"; "the strong man could turn an iron bar")